Manufacture of electric discharge vessels



I June 20, 1933. Q EDEN AL 1,914,634

MANUFACTURE OF ELECTRIC DISCHARGE VESSELS Filed Feb. 17. 1932 r ATTORNEYPatented June- 20, 1933 UNITED STATES PATENT OFFICE CHRISTOPHER GABRIELEDEN, OF CROXLEY GREEN, AND COLIN JAMES SMITHELLS, OF BUSHEY,ENGLAND,'ASSIGNORS TO THE M-O VALVE COMPANY LIMITED, OF LONDON,

ENGLAND MANUFACTURE OF ELECTRIC DISCHARGE VESSELS Application filedFebruary 17, 1932, Serial No. 593,446, and in Great Britain February 19,1931.

This invention relates to methods of sealing olf from the exhaust pumpelectric discharge vessels of the kind in which one of the metalelectrodes forms part of the envelope of the vessel.

The manufacture of an electric discharge vessel of the kind specified,according to the present invention, comprises exhausting the vesselthrough a metal tube attached to the metal part of the envelope, thesaid tube being coated internally with solder prior to exhaustion,compressing and heating the tube so that the solder melts and forms acontinuous layer blocking the bore of the tube, and finally severing thetube beyond the block so formed. It is to be understood that by solderis meant a metal alloy that wets the tube and melts at a lowertemperature than the tube.

The invention will now be described, by way of example, with referenceto the accompanying drawing, which shows various stages in themanufacture of a broadcast receiving valve.

As shown in Figure 1, the envelope of the valve comprises a copperportion 1, which forms the anode, and a lower glass portion 2. Thecopper anode 1 is of cylindrical form and is provided at one end with acopper tube 3. This tube 3 may be formed either by drawing off the topof the anode 1 or a separate tube may be brazed to the end of the anode.The tube 3 is coated internally with a layer of silver solder 4.

When the internal parts of the valve have been assembled and the end ofthe glass portion 2 has been sealed off, the envelope is exhaustedthrough the tube 3. When exhaustion is com lete the tube 3 iscompressed, as shown in igure 2, to constrict the bore of the tubeadjacent to the solder 4 and the tube is heated until the solder meltsand forms a continuous layer blocking the constricted bore of the tube.Finally the tube is cooled and the portion of the tube beyond theblocked part is detached, as shown in Fi re 3, in any convenient manner.If desire the solder may be melted before the tube is compressed or thetwo operations may be performed simultaneously.

We claim 1. In the manufacture of an electric discharge vessel of thekind specified, the process which comprises providing the metal part ofthe envelope with a metal tube projecting from the envelope, coating thetube internally with solder at a point adjacent to the envelope,exhausting the envelope through the tube, compressing the tube upon thesolder at the point coated and melting said solder so that it blocks thecompressed part of the tube.

2. In the manufacture of an electric discharge vessel of the kindspecified, the process which comprises providing the metal part of theenvelope With a metal tube PIOJGCting from the envelope, coating thetube internally with solder at a point adjacent to the envelope,exhausting the envelope through the tube, heating the tube to melt thesolder and compressing the tube upon the solder at the point coated sothat the tube is blocked by the melted solder.

3. In the manufacture of an electric discharge vessel of the kindspecified, the process which comprises drawing off the end of the metalpart of the envelope to form a tube extending from the envelope, coatingthe interior of that part of the tube which is adja-- cent to theenvelope with solder, exhausting the envelope through the tube andclosing the tube by compressing it upon and melting the solder.

'4. In the manufacture of an electric discharge vessel in which acylindricalcopper anode forms part of the envelope of the vessel, theprocess which comprises providing the anode with a metal tubularextension, coating the interior of the extension with solder, exhaustingthe envelope through the extension and closing the extension bycompressing it upon and melting the solder.

5. A sealed electric discharge vessel comprising a metal anode forminpart of the envelope, a metal exhaust tu extending from said anode, theend of which is compressed, and solder within the compressed portion ofthe tube sealing the same.

CHRISTOPHER GABRIEL EDEN.

COLIN JAMES SMITHELLS.

